What is muscle thixotropy?
Thixotropy is the property of some gels to turn into liquids under certain conditions. There is a small degree of stiffness in the normal resting muscle that disappears on voluntary movement or passive muscle stretch. Thixotropy is the physiological term used to describe this component of muscle tone.
What causes thixotropy?
Thixotropy arises because particles or structured solutes require time to organize. Some fluids are anti-thixotropic: constant shear stress for a time causes an increase in viscosity or even solidification. Fluids which exhibit this property are sometimes called rheopectic.
What are the pharmaceutical applications of thixotropy?
The time-dependent change in viscous nature of thixotropy finds its major applications in pharmaceutical formulations including hydrogel, ointment, suspensions and emulsions through various routes including oral, topical, ophthalmic and mucosal administration, as shown in Table 2.
What is Rheopectic fluid?
Rheopecty or rheopexy is the rare property of some non-Newtonian fluids to show a time-dependent increase in viscosity (time-dependent viscosity); the longer the fluid undergoes shearing force, the higher its viscosity. Rheopectic fluids, such as some lubricants, thicken or solidify when shaken.
Are muscles thixotropic?
Because the resistance to movement increases with time at rest and is reduced by movement, this behavior has become known as muscle thixotropy. In this short review, we describe the phenomenon of thixotropy and illustrate its significance in postural control with particular emphasis on human standing.
How do you test thixotropy?
Thixotropy can be quantitatively measured using a rotational rheometer. The most commonly used testing geometries are 20-40 mm parallel plate or a cup/rotor geometry.
What is the negative thixotropy?
Negative thixotropy, also called antithixotropy, is the effect of a flow-induced increase in viscosity that has been observed for many polymer solutions. The model assumes a dynamic gel or network in the polymer solution, whose cross-links are dynamically formed and broken.
Is xanthan gum thixotropic?
Xanthan gum solutions are highly pseudoplastic. When shear stress rate is increased, viscosity decreases. Upon the reduction of shear, initial viscosity is recovered in moments. Xanthan solutions are not thixotropic to a significant degree.
Are thixotropic fluids Newtonian?
In reality most fluids are non-Newtonian, which means that their viscosity is dependent on shear rate (Shear Thinning or Thickening) or the deformation history (Thixotropic fluids).
Is a example of thixotropic fluid?
Other examples of thixotropic fluids are gelatine, shortening, cream, xanthan gum solutions, aqueous iron oxide gels, pectin gels, hydrogenated castor oil, carbon black suspension in molten tire rubber, many floc suspensions, and many colloidal suspensions.
What type of fluid is cornstarch and water?
non-Newtonian fluid
An inexpensive, non-toxic example of a non-Newtonian fluid is a suspension of starch (e.g., cornstarch) in water, sometimes called “oobleck”, “ooze”, or “magic mud” (1 part of water to 1.5–2 parts of corn starch). The name “oobleck” is derived from the Dr. Seuss book Bartholomew and the Oobleck.
Is blood thixotropic?
In our previous studies, we demonstrated that blood is a thixotropic fluid.
What does thixotropy mean in terms of muscle tone?
Not every “tight” muscle is spastic. Thixotropy is the property of some gels to turn into liquids under certain conditions. There is a small degree of stiffness in the normal resting muscle that disappears on voluntary movement or passive muscle stretch. Thixotropy is the physiological term used to describe this component of muscle tone.
What does thixotropy mean in terms of viscosity?
Thixotropy is defined as the progressive decrease in viscosity with time for a constant applied shear stress, followed by a gradual recovery when the stress is removed.
How is thixotropy a property of a gel?
Thixotropy is the property of certain fluids and gels of becoming thinner when a constant force is applied and after reduction of the force the viscosity recovers fully to the initial state in an appropriate period of time i-ii. The higher the force that is applied, the lower the viscosity becomes.
Which is an example of a thixotropic substance?
It means the change or transition of a substance due to mechanical load iv. Examples of thixotropic materials are lotions, gels, ketchup, paints, and gypsum. For example, ketchup flows out of the tube when it is pressed.